Vitamin B2 is a vitamin that functions as a cofactor to flavoenzymes in the intracellular redox system and the mitochondrial electron transport system, and therefore it is widely involved in the metabolism of sugars, lipids, and proteins in the body. Because vitamin B2 plays a role in aiding growth and reproduction; making healthy skin, nails, and hair; easing inflammation in the mouth, lips, and tongue; promoting good vision; and alleviating eye fatigue; and together with other substances, it participates in the metabolism of carbohydrates, lipids, and proteins; aids in the release of energy to various cells; and aids in the formation of red blood cells, it is widely used as an additive in nutritionally supplemented food products.
Vitamin B2 is water soluble and even if it is ingested in excess, the extraneous amount is rapidly excreted from the body, and thus almost no damage resulting from overconsumption occurs. Moreover, vitamin B2 toxicity has not been reported. Therefore, vitamin B2 is often used as an ingredient in supplements in combination with other B-vitamins.
Protein hydrolysate has excellent digestion and absorption properties, and it is widely used as a raw material in supplements and functional foods. Moreover, it has been reported that the various peptides contained in protein hydrolysate have physiological functions such as an antihypertensive effect, muscle fatigue recovery promoting effect, lipid metabolism promoting effect, and an immunostimulatory effect.
It has been found that, however, when a beverage product containing both a protein hydrolysate and vitamin B2 is exposed to light, an off-flavor is generated. Because combinations of protein hydrolysate+vitamin B2+vitamin C are often seen in tablets and powdered form, it appears that this off-flavor problem is specific to liquids.
It is known that vitamin B2 is soluble in water and is resistant to acids and heat, but it will be broken down under strong light or by bases, Therefore, when only vitamin B2 is contained in a liquid, the problem of vitamin B2 photodegradation may occur, whereas no off-flavor will be generated. In addition, if the vitamin B2 photodegradation is the only issue, blocking the light using a dark brown bottle should be effective, but the problem of an off-flavor still could not be solved.
Therefore, a method is needed to solve the problem of the off-flavor that is generated when a beverage containing both a protein hydrolysate and vitamin B2 is exposed to light.
Japanese Patent Application Laid-open No. 2005-110649 discloses a method for improving the undesirable peptide odor by adding an extract of Lo Han Kuo (Momordica grosvenori) and trehalose. Japanese Patent Application Laid-open No. 2006-111566 discloses a method for suppressing the off-flavor in a liquid agent for internal use containing methionine and vitamin B2 by adding a component for inhibiting the generation of active oxygen or a polyglyceryl fatty acid ester.
An object of the present invention is to provide a technique for reducing the off-flavor generated when a combination of protein hydrolysate and vitamin B2 is exposed to light.